Viscosity must be maintained within limits at the operating temperature. Petroleum based Hydraulic oil with a high viscosity index (95 or higher) and a viscosity grade of ISO VG 46 or 68 is optimum.

OptimumViscosity, SUSat 100 degrees F

Fluid CleanlinessLevels ISO/DIS 4406(SAE J1165)

Gear Pump

200-300

19/17/14

Piston Pump

200-300

18/16/13

Geroller Motor

200-300

19/17/14

Vane Motor

200-300

19/17/14

Mobile Spool Valve

19/17/14

Cartridge Valve

18/16/13

The fluid cleanliness levels described can be achieved in systems with normal dirt ingression by filtering one third of the total fluid volume in the system per minute across filter media of suitable dirt holding capacity and with a pore rating of 10 micron absolute (Beta 10 equal or greater than 200).